Display apparatus and its manufacturing method

ABSTRACT

An inexpensive display unit having a sufficient luminance and a method of fabricating the display unit are disposed, wherein micro-sized semiconductor light emitting devices are fixedly arrayed on a plane of a base body of the display unit at intervals. Micro-sized GaN based semiconductor light emitting devices ( 11 ) formed by selective growth are each buried in a first insulating layer ( 21 ) made from an epoxy resin except an upper end portion and a lower end surface thereof, and electrodes ( 18 ) and ( 19 ) of each of the light emitting devices ( 11 ) are extracted. These light emitting devices ( 11 ) are fixedly arrayed on the upper plane of the base body ( 31 ) at intervals. A second insulating layer ( 34 ) made from an epoxy resin is formed on the plane of the base body ( 31 ) so as to cover the semiconductor light emitting devices ( 11 ) each of which has been buried in the first insulating layer ( 21 ) The electrodes ( 18 ) and ( 19 ) are extracted to the upper surface of the second insulating layer ( 34 ) via specific connection holes formed in the second insulating layer ( 34 ), and the electrode ( 18 ) is led to a connection electrode ( 32 ) provided on the base body ( 31 ) via a connection hole formed in the second insulating layer ( 34 ).

TECHNICAL FIELD

[0001] The present invention relates to a display unit and a method offabricating the display unit, and particularly to a display unitincluding a plurality of micro-sized semiconductor light emittingdevices arrayed on a plane of a base body at intervals and a method offabricating the display unit. In more particular, the present inventionrelates to a display unit including an array of semiconductor lightemitting devices each having a large luminance and a method offabricating the display unit.

BACKGROUND ART

[0002] Display units of a type using light emitting diodes (LEDs) as alight emitting source, as shown in FIG. 10, are known. FIG. 10 is aperspective view showing a rear side of an essential portion of oneexample of such related art display units. Referring to this figure, adisplay unit 100 is fabricated by two-dimensionally, densely arrayingexpensive LED modules 102, the size of each of which is standardizedinto a relatively large value (for example, 5 mm square), on a plane 101of a base body and fixing them thereon, and connecting an anodeelectrode 103 and a cathode electrode 104 of each of the LED modules 102to wiring provided on the base body by wire bonding or soldering. Thisrelated art display unit 100 has the following problem. An LED chiphaving a size being usually about 0.3 mm square cut out of a compoundsemiconductor wafer is used for the LED module 102 per one pixel, andtherefore, a large number of the compound semiconductor wafers arerequired to provide the LED chips used for several hundreds of thousandsof pixels constituting the full-screen of the display unit 100, with aresult that the material cost is raised. Another problem of the relatedart display unit 100 is that since additional equipment and workingsteps are required for arraying and fixture of the LED modules andconnection of the electrodes to wiring by wire bonding or soldering, thefabrication cost is essentially raised.

[0003] Each of the LED chips used for the related art display unit 100has been usually of a planar type typically shown in FIG. 11, wherein ap-type semiconductor 106 having a p-electrode 107 and an n-typesemiconductor 108 having an n-electrode 109 are stacked in a planestructure with an active layer 105 sandwiched therebetween. Lightemitted from the active layer 105 is basically directed inomni-directions; however, due to a relationship between a relativelylarge refractive index of the semiconductor and an incident angle fromthe interior of the semiconductor to the interface (surface), lightdirected in the vertical direction is mainly emerged to the outsidethrough the interface. As a result, there occur problems that the lightemission efficiency in the downward direction is low even inconsideration of the fact that the light directed upwardly (rear surfaceside) is reflected from an electrode plane or the like to the lower side(front surface side), and that the light emitted to the rear surfaceside is made incident on the adjacent LED module to cause bleeding in animage displayed on the display unit.

[0004] Taking into account the above-described problems, the presentinvention has been made, and an object of a first object is to provide adisplay unit fabricated at a low cost by arraying micro-sizedsemiconductor light emitting devices at intervals and simply fixing themthereon, and a method of fabricating the display unit. A second objectof the present invention is to provide a display unit includingsemiconductor light emitting devices each of which is of a micro-sizeand has a sufficient luminance, and a method of fabricating the displayunit.

[0005] As one specific related art example, a display unit capable ofreducing the cost and improving the reliability by using light emittingdiodes buried in an insulating material has been disclosed in JapanesePatent Laid-open No. Sho 57-45583. The light emitting diode used in thisdisplay unit, however, is a light emitting diode chip having a planarstructure cut out of a wafer, and an anode electrode and a cathodeelectrode have been mounted on each of the chips in the wafer state.Also, an epoxy resin used as an insulating layer to bury spaces amongthe light emitting diodes fixedly arrayed on a substrate is poured andcured such that the upper surface of the insulating layer issubstantially at the same level as the upper end surfaces of the lightemitting devices, and the upper surface of the insulating layer issmoothened by lapping or the like.

[0006] Japanese Patent Laid-open No. Hei 3-35568 has disclosed a lightemitting diode having a small pn-junction region, wherein an upper endside of a semiconductor portion taken as an optical path over thepn-junction is cut into a truncated pyramid shape in order tosignificantly improve the rate of light emerged outwardly from theinside of the light emitting diode through the interface between thelight emitting diode and an outer transparent plastic. The refractiveindex of the light emitting diode is greatly different from that of thetransparent plastic around the light emitting diode. Accordingly, oflight directed from a point light source to the interface, a lightcomponent entering the interface in the direction perpendicular to theinterface, that is, at an incident angle of 0° and a light componenthaving an incident angle smaller than a conical angle (for example, 27°)centered at the point light source pass through the interface; however,other light components each having a large incident angle are reflectedfrom the interface and thereby impossible to be emerged outwardly fromthe inside of the light emitting diode, and are repeatedly reflectedfrom the interface to be decayed. The cutting the upper end side of thesemiconductor portion into the truncated pyramid shape is made to avoidsuch a phenomenon as much as possible.

[0007] Japanese Patent Laid-open No. Hei 11-75019 has disclosed a lightsource unit using light emitting diodes, wherein a tilt mirror tilted at45° is provided at a position over a semiconductor chip as the lightemitting diode. The mirror is provided for allowing light emittedupwardly from the light emitting diode to be reflected from the mirrorat right angles, that is, toward the horizontal direction, and as such amirror, there is used a dichroic mirror for reflecting light emittedfrom the light emitting diodes for emission of light of blue, green, andred onto the same optical axis.

DISCLOSURE OF INVENTION

[0008] The above-described problems are solved by a configuration of aninvention described in claim 1, 10 or 13. Such solving means describedin the invention are as follows:

[0009] According to the invention described in claim 1, there isprovided a display unit including a plurality of semiconductor lightemitting devices mounted in array on a plane of a base body,characterized in that the semiconductor light emitting devices arefixedly arrayed on the plane of the base body at intervals in a statebeing buried in a first insulating layer or in a bare state being notburied in the first insulating layer; a second insulating layer isformed on the plane of the base body so as to cover the semiconductorlight emitting devices; and an upper end side electrode and a lower endside of each of the semiconductor light emitting devices are extractedvia connection holes formed in specific positions of the firstinsulating layer and the second insulating layer.

[0010] With this display unit, since the semiconductor light emittingdevices are fixedly arrayed on the plane of the base body at intervalsin a state being buried in the first insulating layer or in a bare statebeing not buried in the first insulating layer, and the electrodes ofeach of the semiconductor light emitting devices are extracted via theconnection holes formed in the second insulating layer covering thesemiconductor light emitting devices, it is possible to significantlyreduce the cost per unit area of the display unit.

[0011] According to an invention described in claim 2, there is provideda display unit according to claim 1, wherein the semiconductor lightemitting devices are fixedly arrayed on the plane of the base body in astate being buried in the first insulating layer except the upper endportions and the lower end portions of the semiconductor light emittingdevices; the upper end side electrode and the lower end side electrodeof each of the semiconductor light emitting devices are extracted to theupper surface of the first insulating layer and then extracted to theupper surface of the second insulating layer; and either of theelectrodes is led to a connection electrode provided on the plane of thebase body. With this display unit, since each of the semiconductor lightemitting devices is buried in the first insulating layer to form aresin-covered chip having a large size, it is possible to facilitate thehandling of the semiconductor light emitting device, and since oneelectrode is connected to a drive circuit on the upper surface of thesecond insulating layer and the other electrode is connected to a drivecircuit on the plane of the base body, the drive circuits for theelectrodes located in the directions perpendicular to each other do notcross each other, so that it is possible to simplify the wiring.

[0012] According to an invention described in claim 3, there is provideda display unit according to claim 1, wherein the semiconductor lightemitting devices are fixedly arrayed on the plane of the base body inthe state being bared; the second insulating layer is formed on theplane of the base body so as to cover the semiconductor light emittingdevices; the upper end side electrode and the lower end side electrodeof each of the semiconductor light emitting devices are extracted to theupper surface of the second insulating layer; and either of theelectrodes is led to a connection electrode provided on the plane of thebase body. With this display unit, since the first insulating layer inwhich the semiconductor light emitting devices are to be buried is notprovided, some ingenuity is required in handling the semiconductor lightemitting devices; however, it is possible to omit the device buryingstep, and since one electrode is connected to a drive circuit on theupper surface of the second insulating layer and the other electrode isconnected to a drive circuit on the plane of the base body, the drivecircuits for the electrodes located in the directions perpendicular toeach other do not cross each other, thereby simplifying the wiring.

[0013] According to an invention described in claim 4, there is provideda display unit according to claim 1, wherein each of the firstinsulating layer and the second insulating layer is made from a polymercompound formable into a coating film, the polymer compound beingselected from a polyimide resin, an ultraviolet curing resin, an epoxyresin, and a synthetic rubber. With this display unit, it is possible toeasily form the insulating layer even on the plane, having a large area,of the base body by coating, and hence to simplify the mounting of thesemiconductor light emitting devices on the plane of the base body.

[0014] According to an invention described in claim 5, there is provideda display unit according to claim 1, wherein each of the semiconductorlight emitting devices mainly emits light in a direction from a lightemission region to the lower end plane, mounted on the plane of the basebody, of the semiconductor light emitting device; and the semiconductorlight emitting device has, at a position over the light emission region,a reflection mirror from which the light is reflected downwardly. Withthis display unit, it is possible to effectively direct light from thelight emission region to the lower end plane of the semiconductor lightemitting device by means of the reflection mirror.

[0015] According to an invention described in claim 6, there is provideda display unit according to claim 5, wherein the semiconductor lightemitting device is formed into a pyramid shape or a truncated pyramidshape; and any one of at least tilt planes among planes of the pyramidor truncated pyramid shaped semiconductor light emitting device is takenas the reflection mirror. With this display unit, since the tilt planesof the polygonal pyramid or the truncated polygonal pyramid can be takenas reflecting planes, or the upper plane of the truncated polygonalpyramid can be taken as a reflection mirror, it is possible toconcentrate light emitted from the light emission region to the lowerend plane of the semiconductor light emitting device.

[0016] According to an invention described in claim 7, there is provideda display unit according to claim 6, wherein the semiconductor lightemitting device is made from a gallium nitride based semiconductorhaving a hexagonal system; and the semiconductor light emitting deviceincludes an active layer formed in parallel to a (1-101) plane. Withthis display unit, since a light emission efficiency of the active layerformed in parallel to the (1-101) plane of the gallium nitride basedsemiconductor is high and an electrode plane provided on the (1-101)plane can be taken as a reflection mirror, it is possible to enhance thelight emission characteristic.

[0017] According to an invention described in claim 8, there is provideda display unit according to claim 7, wherein the semiconductor lightemitting device is made from a gallium nitride based semiconductorformed by crystal growth on a growth substrate into a hexagonal pyramidshape or a truncated hexagonal pyramid shape with a (0001) plane takenas the lower end plane and (1-101) planes and planes equivalent theretotaken as the tilt planes; and the semiconductor light emitting deviceincludes an active layer formed in parallel to the (1-101) planes andplanes equivalent thereto. With this display unit, since the lightemission efficiency of the active layer formed in parallel to the(1-101) plane of the gallium nitride based semiconductor is high and anelectrode plane provided on the (1-101) plane can be taken as areflection mirror, it is possible to concentrate light emitted from thelight emission region to the lower end plane of the semiconductor lightemitting device and particularly enhance the light emissioncharacteristic.

[0018] According to an invention described in claim 9, there is provideda display unit according to claim 1, wherein the display is an imagedisplay unit or a lighting unit including an array of only one kind ofthe semiconductor light emitting devices allowing emission of light of asingle color, or an array of a combination of a plurality of kinds ofthe semiconductor light emitting devices allowing emission of light ofdifferent colors. Such a display unit can usable as an image displayunit or a lighting unit having a high luminance, which includes lightemitting diodes or semiconductor lasers.

[0019] According to the invention described in claim 10, there isprovided a method of fabricating a display unit including a plurality ofsemiconductor light emitting devices on a plane of a base body,characterized by including the steps of: burying the semiconductor lightemitting devices in a first insulating layer, forming specificconnection holes in the first insulating layer, and extracting an upperend side electrode and a lower end side electrode of each of thesemiconductor light emitting devices via the connection holes formed inthe first insulating layer; fixedly arraying semiconductor lightemitting devices, from each of which the electrodes have been extracted,on the plane of the base body at intervals; forming a second insulatinglayer so as to cover the semiconductor light emitting devices each ofwhich has been buried in the first insulating layer; and formingspecific connection holes in the second insulating layer, and extractingthe upper end side electrode and the lower end side electrode of each ofthe semiconductor light emitting devices having been extracted to theupper surface of the first insulating layer via the connection holes.With this method of fabricating a display unit, since each of thesemiconductor light emitting devices is buried in the first insulatinglayer to form a resin-covered chip having a large size, it is possibleto facilitate the handling of the light emitting devices and hence toeasily array the light emitting devices on the plane of the base body atintervals, and since the second insulating layer is formed so as tocover the light emitting devices and then the electrodes of each of thelight emitting devices are extracted via the connection holes formed inthe second insulating layer and connected to drive circuits, it ispossible to provide the display unit capable of significantly reducingthe cost per unit area of the display unit.

[0020] According to an invention described in claim 11, there isprovided a method of fabricating a display unit according to claim 10,wherein each of the semiconductor light emitting devices is buried inthe first insulating layer except an upper end portion and a lower endplane thereof, and the upper end side electrode and the lower end sideelectrode are extracted to the upper surface of the first insulatinglayer. With this method of fabricating a display unit, it is possible toprovide the display unit capable of facilitating the extraction of theupper end side electrode, and preventing a reduction in light emissionarea due to extraction of the lower end side electrode to the lower endplane.

[0021] According to an invention described in claim 12, there isprovided a method of fabricating a display unit according to claim 10,wherein the upper end side electrode and the lower end side electrode ofeach of the semiconductor light emitting devices having been extractedto the upper surface of the first insulating layer are both extracted tothe upper surface of the second insulating layer; and either of theelectrodes is led to a connection electrode provided on the plane of thebase body. With this method of fabricating a display unit, since oneelectrode is connected to a drive circuit on the upper surface of thesecond insulating layer and the other electrode is connected to a drivecircuit on the plane of the base body, the drive circuits for theelectrodes located in the directions perpendicular to each other do notcross each other, so that it is possible to provide the display unitcapable of simplifying the wiring.

[0022] According to the invention described in claim 13, there isprovided a method of fabricating a display including a plurality ofsemiconductor light emitting devices mounted in array on a plane of abase body, characterized by including the steps of: fixedly arraying thesemiconductor light emitting devices on the plane of the base body atintervals in a state being bared; forming a second insulating layer onthe plane of the base body so as to cover the semiconductor lightemitting devices; and forming specific connection holes in the secondinsulating layer, and extracting an upper end side electrode and a lowerend side electrode of each of the semiconductor light emitting devicesvia the connection holes. With this method of fabricating a displayunit, since the semiconductor light emitting devices, each of which isin the state being bared, that is, with its size not enlarged, arearrayed on the plane of the base body at intervals, some ingenuity isrequired in handling the semiconductor light emitting devices; however,it is possible to omit the device burying step, and to significantlyreduce the cost per unit area of the display unit.

[0023] According to an invention described in claim 14, there isprovided a method of fabricating a display unit according to claim 13,wherein the upper end side electrode and the lower end side electrode ofeach of the semiconductor light emitting devices in the state beingbared are extracted to the upper surface of the second insulating layer;and either of the electrodes is led to a connection electrode providedon the plane of the base body. With this method of fabricating a displayunit, it is possible to prevent a reduction in light emission area dueto extraction of the lower end side electrode to the lower end plane ofthe semiconductor light emitting device. Also, since one electrode isconnected to a drive circuit on the upper surface of the secondinsulating layer and the other electrode is connected to a drive circuiton the plane of the base body, the drive circuits for the electrodeslocated in the directions perpendicular to each other do not cross eachother. As a result, it is possible to simplify the wiring.

[0024] According to an invention described in claim 15, there isprovided a method of fabricating a display unit according to claim 10 or13, wherein each of the first insulating layer and the second insulatinglayer is made from a polymer compound formable into a coating film, thepolymer compound being selected from a polyimide resin, an ultravioletcuring resin, an epoxy resin, or a synthetic rubber. With this method offabricating a display unit, it is possible to easily form the insulatinglayer even on the plane, having a large area, of the base body bycoating, and hence to simplify the mounting of the semiconductor lightemitting devices on the plane of the base body.

[0025] According to an invention described in claim 16, there isprovided a method of fabricating a display unit according to claim 10 or13, wherein each of the semiconductor light emitting devices mainlyemits light in a direction from a light emission region to the lower endplane, mounted on the plane of the base body, of the semiconductor lightemitting device; and the semiconductor light emitting device has, at aposition over the light emission region, a reflection mirror from whichthe light is reflected downwardly. With this method of fabricating adisplay unit, it is possible to provide the display unit capable ofeffectively directing light from the light emission region to the lowerend plane of the semiconductor light emitting device by means of thereflection mirror.

[0026] According to an invention described in claim 17, there isprovided a method of fabricating a display unit according to claim 16,wherein the semiconductor light emitting device is formed into a pyramidshape or a truncated pyramid shape; and any one of at least tilt planesamong planes of the pyramid or truncated pyramid shaped semiconductorlight emitting device is taken as the reflection mirror. With thismethod of fabricating a display unit, it is possible to provide thedisplay unit capable of concentrating light emitted from the lightemission region to the lower end plane of the semiconductor lightemitting device by using the tilt planes of the polygonal pyramid or thetruncated polygonal pyramid as the reflection mirrors or using the upperplane of the truncated polygonal pyramid as the reflection mirror.

[0027] According to an invention described in claim 18, there isprovided a method of fabricating a display unit according to claim 17,wherein the semiconductor light emitting device is made from a galliumnitride based semiconductor having a hexagonal system; and thesemiconductor light emitting device includes an active layer formed inparallel to a (1-101) plane. With this method of fabricating a displayunit, since the gallium nitride based semiconductor exhibits a highlight emission efficiency at the (1-101) plane, it is possible toprovide the display unit having an excellent light emissioncharacteristic.

[0028] According to an invention described in claim 19, there isprovided a method of fabricating a display unit according to claim 18,wherein the semiconductor light emitting device is made from a galliumnitride based semiconductor formed by crystal growth on a growthsubstrate into a hexagonal pyramid shape or a truncated hexagonalpyramid shape with a (0001) plane taken as the lower end plane and(1-101) planes and planes equivalent thereto taken as the tilt planes;and the semiconductor light emitting device includes an active layerformed in parallel to the (1-101) planes and planes equivalent thereto.With this method of fabricating a display unit, since light emission isconcentrated to the lower end plane of the semiconductor light emittingdevice with an electrode plane provided on the (1-101) plane parallel tothe active layer exhibiting a high light emission efficiency taken asthe reflection mirror, it is possible to provide the display unit havingan excellent light emission characteristic.

BRIEF DESCRIPTION OF DRAWINGS

[0029]FIG. 1 is a sectional view showing a state that a micro-sized GaNbased semiconductor light emitting device is buried in a firstinsulating layer (epoxy resin) except an upper end portion and a lowerend plane of the light emitting device;

[0030]FIG. 2 is a sectional view showing a state, subsequent to thestate shown in FIG. 1, that a connection hole is formed in the uppersurface of the first insulating layer to a depth reaching a lower endside electrode of the GaN based semiconductor light emitting device, analuminum film is formed over the entire surface of the first insulatinglayer by vapor-deposition or sputtering and is patterned byphotolithography and etching, and a p-electrode on the upper end sideand an n-electrode on the lower end side are extracted to the uppersurface of the first insulating layer;

[0031]FIGS. 3A and 3B are a vertical sectional view and a plan viewshowing a detail structure of a GaN based semiconductor light emittingdevice formed into a hexagonal pyramid shape by crystal growth,respectively;

[0032]FIG. 4 is a sectional view showing a state that the GaN basedsemiconductor light emitting devices shown in FIG. 2 are arrayed on atransparent base body of a display unit at specific intervals and fixedthereon with a transparent adhesive, and then a second insulating layer(epoxy resin) is formed so as to cover the GaN based semiconductor lightemitting devices;

[0033]FIG. 5 is a sectional view showing a state, subsequent to thestate shown in FIG. 4, that connection holes are formed at specificpositions of the second insulating layer, and the p-electrode and then-electrode having been extracted on the upper surface of the firstinsulating layer are extracted to the upper surface of the secondinsulating layer and further the p-electrode is led to a connectionelectrode provided on the plane of the base body via the connectionholes;

[0034]FIG. 6 is a sectional view showing a state that bare GaN basedsemiconductor light emitting devices not buried in any first insulatinglayer are arrayed on a transparent base body of a display unit atspecific intervals and fixed thereon with a transparent adhesive, andthen a second insulating layer is formed so as to cover the GaN basedsemiconductor light emitting devices;

[0035]FIG. 7 is a sectional view showing a state, subsequent to thestate shown in FIG. 6, that connection holes are formed at specificpositions of the second insulating layer, and a p-electrode and ann-electrode of each of the bare GaN based semiconductor light emittingdevices are extracted to the upper surface of the second insulatinglayer and further the n-electrode is led to a connection electrodeprovided on the plane of the base body via the connection holes;

[0036]FIG. 8 is a sectional view of a GaN based semiconductor lightemitting device formed into a truncated hexagonal pyramid shape bycrystal growth;

[0037]FIG. 9 is a perspective view of a truncated hexagonal pyramidshaped GaN based semiconductor light emitting device formed by crystalgrowth from an opening portion of a rectangular mask longer in aspecific direction;

[0038]FIG. 10 is a perspective view of a rear side of an essentialportion of a related art display unit including light emitting diodes,in which relatively large standardized size of modules are denselyarrayed; and

[0039]FIG. 11 is a sectional view typically showing a light emittingdiode.

BEST MODE FOR CARRYING OUT THE INVENTION

[0040] As described above, according to the present invention, there areprovided a display unit including a plurality of semiconductor lightemitting devices mounted in array on a plane of a base body, and amethod of fabricating the display unit. The semiconductor light emittingdevices are fixedly arrayed on the plane of the base body at intervalsin a state being buried in a first insulating layer or in a bare statebeing not buried in the first insulating layer. A second insulatinglayer is formed on the plane of the base body so as to cover thesemiconductor light emitting devices. An upper end side electrode and alower end side of each of the semiconductor light emitting devices areextracted via connection holes formed in specific positions of the firstinsulating layer and the second insulating layer.

[0041] The semiconductor light emitting device used for the display unitmay be configured such that when a current is injected to a junctionplane between a p-type semiconductor and an n-type semiconductor in thenormal direction, positive holes and electrons as carriers arerecombined with each other, to thereby cause light emission. Thematerials for forming the semiconductor light emitting device are notparticularly limited. As the semiconductor allowing emission of light,there is known a gallium based compound semiconductor, examples of whichinclude gallium nitride (GaN) allowing emission of blue light, galliumphosphide (GaP) allowing emission of green light, gallium arsenicphosphide (GaAsP) allowing emission of red light, and aluminum galliumarsenide (AlGaAs) In addition, zinc selenide (ZnSe) or silicon carbide(SiC) is known as a material allowing emission of light of course, anyother material allowing emission of light may be used.

[0042] For a semiconductor light emitting device including GaN basedsemiconductors, a p-type GaN based semiconductor is obtained by dopingan acceptor impurity such as Mg, Zn, or C in crystal and an n-type GaNbased semiconductor is obtained by doping a doner impurity such as Si,Ge, or Se in crystal, and the pn-junction is preferably configured as ahetero-junction, more preferably, as a double hetero-junction in whichan active layer made from InGaN is sandwiched between an n-type claddinglayer made from GaN based semiconductor doped with Si and a p-typecladding layer made from a GaN based semiconductor doped with Mg. Thesemiconductor light emitting device having such a configuration is ableto exhibit a significantly excellent light emission characteristic. Inaddition, the active layer may be of a single bulk structure or aquantum well structure.

[0043] The compound semiconductor as the material of the semiconductorlight emitting device is fabricated by a metalorganic chemical vapordeposition (MOCVD) process, a molecular beam epitaxy (MBE) process, or ahydride vapor-phase epitaxy (HVPE) process, and therefore, the compoundsemiconductor is expensive. Accordingly, the size of the semiconductorlight emitting device is desirable to be made as small as possibleinsofar as it is allowed to be handled. Such micro-sized semiconductorlight emitting devices can be obtained by fabricating a compoundsemiconductor wafer for semiconductor light emitting devices and cuttingthe wafer into chips; however, they can be more easily fabricated byselective crystal growth of compound semiconductors, for example, on asapphire substrate. For example, semiconductor light emitting deviceseach having a size (length of one size of the lower end plane) in arange of about 100 to 200 μm or less, particularly, in a range of about10 to 50 μm can be obtained by such selective crystal growth. If needed,each of the semiconductor light emitting devices thus formed by crystalgrowth may be subjected to a treatment of adjusting a three-dimensionalshape thereof.

[0044] For the micro-sized semiconductor light emitting device thusobtained, a p-electrode made from typically Ni/Au is mounted to thep-type semiconductor by vapor-deposition, and an n-electrode made fromtypically Ti/Au is mounted to the n-type semiconductor. The micro-sizedsemiconductor light emitting device provided with the electrodes may befixedly arrayed on a plane of a base body as it is; however, tofacilitate the handling of the micro-sized semiconductor light emittingdevice, the light emitting device may be buried in a first insulatinglayer to form a resin-covered chip having a large apparent size, andthen the resin-covered chip be fixedly arrayed on the plane of the basebody. To improve the light emission characteristic toward the frontsurface side of the display unit, the three-dimensional shape of each ofthe semiconductor light emitting devices constituting the display unitis required to be taken into account. Hereinafter, there will bedescribed the arraying and fixture of micro-sized semiconductor lightemitting devices on a plane of a transparent base body taken as a frontpanel of a display unit and the shape of each of the micro-sizedsemiconductor light emitting devices required for enhancing the lightemission characteristic toward the front surface side of the displayunit.

[0045] [Arraying of Micro-Sized Semiconductor Light Emitting Device inthe Form of Chip Having Large Apparent Size]

[0046] The arraying of micro-sized semiconductor light emitting devicesin the form of chips having large apparent sizes will be describedbelow. Micro-sized semiconductor light emitting devices (size: forexample, 10 to 100 μm) formed on a plane of a growth substrate bycrystal growth are fixed on a plane of a transparent support with aspecific pitch (for example, 100 to 300 μm), and a first insulatinglayer is formed so as to bury the semiconductor light emitting devicesexcept the upper end portions and lower end planes thereof and is dicedinto resin-covered chips having large apparent sizes. In this case, thedicing is made such that the micro-sized semiconductor light emittingdevice is located at a central portion of the resin-covered chip. Thereason why the upper end portion of each of the semiconductor lightemitting device is not buried in the first insulating layer is that anelectrode is to be extracted from the upper end portion, and the reasonwhy the lower end plane of each of the semiconductor light emittingdevices is not buried in the first insulating layer is that the lowerend plane is taken as a light emergence plane. It is to be noted thatthe electrode may be extracted to the lower end plane. A polyimideadhesive may be used to fix the GaN based semiconductor light emittingdevices to the transparent support. In this case, by irradiating thepolyimide adhesive with laser beams from the transparent support side asneeded, the transparent support can be easily removed from thesemiconductor light emitting devices due to laser abrasion of polyimide.Alternatively, an ultraviolet-curing sticker may be used to fix the GaNbased semiconductor light emitting devices to the transparent support.In this case, by irradiating the ultraviolet-curing sticker with laserbeams from the transparent support side after formation of the firstinsulating layer, to cure the sticker, thereby eliminating thestickiness of the sticker, so that the transparent support can be easilyremoved from the semiconductor light emitting devices.

[0047] The material of the first insulating layer may be either anorganic matter or an inorganic matter, and the kind and formation mannerthereof are not particularly limited; however, from the viewpoint ofreducing the cost of a display unit, the use of an organic matter issuperior to the use of an inorganic matter. The reason for this is thatalthough an insulating layer made from an inorganic matter such as SiO₂or Si₃N₄ is required to be formed by a CVD (Chemical Vapor Deposition)process, a vapor-deposition process, or a sputtering process, aninsulating layer made from an organic matter, for example, a polymercompound such as an epoxy resin, a polyimide resin, or a syntheticrubber can be easily formed by a simple coating process even if a planeof a base body has a large area. In addition, a spin-on-glass film canbe used as an insulating film formed by coating.

[0048] Since the semiconductor light emitting devices having been buriedin the first insulating layer and diced into resin-covered chips will befixedly arrayed on a plane of a base body with a specific pitch (forexample, 300 to 900 μm) and then buried in a second insulating layer,electrodes are preferably extracted from each of the semiconductor lightemitting devices for easy connection to drive circuit. Assuming that ap-electrode is provided on the upper end portion and an n-electrode isprovided on the lower end portion, a conductive metal is formed on thefirst insulating layer to cover the p-electrode on the exposed upper endportion. As a result, the p-electrode can be extracted to the conductivemetal having a large area on the upper surface of the first insulatinglayer. Accordingly, it is possible to form a connection hole extendingfrom a second insulating layer to the conductive metal (connected to thep-electrode) on the first insulating layer without occurrence of anypositional deviation thereof.

[0049] With respect to the extraction of the n-electrode, a connectionhole is formed in the upper surface of the first insulating layer to adepth reaching the n-electrode on the lower end portion and a conductivemetal is formed on the upper surface of the first insulating layer so asto bury the connection hole, so that the n-electrode can be extracted tothe conductive metal having a large area on the upper surface of thefirst insulating layer. In addition, as described above, the n-electrodemay be extracted to the lower end plane of the semiconductor lightemitting device. In this case, since the lower end plane is taken as alight emission plane, a transparent extraction electrode may be providedin order not to obstruct light emission outward from the lower endplane.

[0050] The semiconductor light emitting devices in the form of theresin-covered chips each having a large apparent size are, as describedabove, fixedly arrayed on a transparent base body taken as a displaypanel of a display unit with a pitch of about 300 to 900 μm. In general,the semiconductor light emitting devices are one-dimensionally ortwo-dimensionally arrayed; however, they may be three-dimensionallyarrayed. The fixture of the semiconductor light emitting devices havingbeen arrayed may be performed in the same manner as that used forburying the semiconductor light emitting devices in the first insulatinglayer to form the resin-covered chips each having a large apparent size.That is to say, a second insulating layer is formed on the plane of thebase body to cover the semiconductor light emitting devices having beenfixedly arrayed on the plane of the base body. The second insulatinglayer may be made from an inorganic matter or an organic matter;however, the second insulating layer is preferably made from the samematerial as that forming the first insulating layer. If the secondinsulating layer is made from an insulating material different from thatforming the first insulating layer, there may occur a lack of anadhesive force at the interface between the stacked first and secondinsulating layers or a problem caused by a difference in thermalexpansion coefficient therebetween.

[0051] After the semiconductor light emitting devices each of which hasbeen buried in the first insulating layer are covered with the secondinsulating layer, the p-electrode and the n-electrode of each of thesemiconductor light emitting devices extracted to the upper surface ofthe first insulating layer are further extracted to the upper surface ofthe second insulating layer and connected to respective drive circuits.The connection of the electrodes can be made by various methods. Oneexample of the connection methods is as follows: namely, two connectionholes are formed in the upper surface of the second insulating layer todepths reaching the upper surface of the first insulating layer, and thep-electrode and the n-electrode are extracted to the upper surface ofthe second insulating layer via the connection holes; and for example,the extracted p-electrode is connected to the corresponding drivecircuit on the upper surface of the second insulating layer, and theextracted n-electrode is connected to a conductive metal buried in aconnection hole formed in the second insulating layer to a depthreaching a connection electrode on the plane of the base body, to bethus connected to the corresponding drive circuit on the plane of thebase body via the connection electrode.

[0052] [Arraying Micro-Sized Semiconductor Device as Being Bared]

[0053] If each of micro-sized semiconductor light emitting devices has asize of about 100 to 200 μm, they can be directly, fixedly arrayed on aplane of a transparent base body in a state being bared, that is,without being buried in an insulating layer to form resin-covered chipseach having a large apparent size. Even semiconductor light emittingdevices each having a size of 100 μm or less can be of course handled asbeing bared. Upper end portions of bared semiconductor light emittingdevices may be picked up and arrayed on a plane of a base body with aspecific pitch by making use of means such as attraction under vacuumand release under atmospheric pressure, or stickiness by anultraviolet-curing sticker and elimination of the sticky force of thesticker by irradiation thereof with ultraviolet light from the base bodyplane side.

[0054] Specifically, semiconductor light emitting devices picked up arefixedly arrayed on a plane of a base body coated with a transparentadhesive with a pitch of, for example, 300 to 900 μm. In this case, thelower end planes of the semiconductor light emitting devices may becoated with a transparent adhesive. Subsequently, a second insulatinglayer is directly formed so as to cover the semiconductor light emittingdevices having been adhesively fixed to the plane of the base body. Theextraction of electrodes of each of the semiconductor light emittingdevices to the upper surface of the second insulating layer may beperformed in the same manner as that used for extracting the electrodesof each of the semiconductor light emitting devices to the upper surfaceof the first insulating layer covering the semiconductor light emittingdevices to form the resin-covered chips each having a large apparentsize.

[0055] [Three-Dimensional Shape of Semiconductor Light Emitting Device]

[0056] With respect to each of semiconductor light emitting devicesfixedly arrayed on a plane of a transparent base body, the luminance ofthe light emitting device toward the base body plane side, that is,toward the lower end plane side of the device can be improved bychanging the shape of the device of light emitted from a light emissionregion (active layer) of a semiconductor light emitting device, a lightcomponent directed upwardly from the light emission region can bedirected to the lower end plane side by using an electrode plane or thelike on the upper end portion as a reflection mirror; however, a lightcomponent directed to a side plane perpendicular to the lower end planeis less directed toward the lower end plane even if being reflected fromthe side plane. Accordingly, the semiconductor light emitting device isdesirable to have a tilt plane tilted from the lower end plane at anangle in a range of 45±20°. By providing a reflection mirror on such atilt plane, the light component directed sideways is reflected from thereflection mirror, to be effectively directed to the lower end plane.The tilt plane is not necessarily configured as a smooth plane such as amirror plane. It is to be noted that in the case where the tilt plane istilted from the lower end plane at an angle out of the above-describedrange, even if the light component directed sideways is reflectedtherefrom, the quantity of light directed to the lower end plane is notincreased so much, thereby failing to obtain the effect of enhancing theluminance.

[0057] The tilt plane may be a shed roof like tilt plane, a gable rooflike tilt plane, or a pavilion roof like tilt plane. Also, asemiconductor light emitting device may be formed into a pyramid shapeor a truncated pyramid shape- The tilt plane of such a pyramid shape ora truncated pyramid shape, or an upper plane of the truncated pyramidshape can be taken as a reflection mirror. With this configuration, itis possible to more effectively direct light emitted from a lightemission region to the lower end plane of the semiconductor lightemitting device. The term “pyramid” includes a triangular pyramid, aquadrangular pyramid, a pentagonal pyramid, a hexagonal pyramid, and apolygonal pyramid close to a cone, and the term “truncated pyramid”includes truncated pyramids corresponding to the above pyramids.Further, a semiconductor light emitting device may have, in its upperend portion, a caldera-shaped recess having a tilt plane in the aboverange of 45±20°. The semiconductor light emitting having theabove-describe tilt plane may be naturally obtained by selective crystalgrowth or may be obtained by surface working after selective crystalgrowth. Alternatively, when a wafer is cut into micro-sizedsemiconductor light emitting devices, a tilt plane may be given to eachof the semiconductor light emitting device. As working means for givingthe above tilt plane, ion beams or laser beams may be used.

[0058] Of compound semiconductors used for semiconductor light emittingdevices, gallium phosphide (GaP) allowing emission of green light, orgallium arsenic phosphide (GaAsP) or aluminum gallium arsenide allowingemission of red light belongs to a cubic system and is formed into ahexahedron shape by selective crystal growth, and accordingly, thecompound semiconductor has no tilt plane with respect to the lower endplane. For such a compound semiconductor, therefore, it may be desirableto provide a tilt plane as a reflection mirror after selective crystalgrowth. On the other hand, a GaN based semiconductor allowing emissionof blue light belongs to a hexagonal system and has a hexagonal columnor hexagonal pyramid shape crystal structure, and more specifically,when the GaN semiconductor is formed on a (0001) plane of a sapphiresubstrate by sufficient selective crystal growth, the GaN basedsemiconductor has a hexagonal pyramid shaped crystal structure includinga (1-101) plane tilted from the lower end plane and a plane equivalentthereto, and when the GaN based semiconductor is formed by lessselective crystal growth, the GaN based semiconductor has a truncatedpyramid shaped crystal structure. Further, Japanese Patent No. 2830814describes a semiconductor formed on a (1-101) plane of a sapphiresubstrate by selective crystal growth has a trapezoidal cross-section inwhich an upper plane parallel to the lower end plane becomes the (1-101)plane, and tilt planes on both sides become the (1-101) plane and a(0111) plane. The semiconductor light emitting device of the presentinvention may be a semiconductor light emitting device having theabove-described tilt plane. By the way, a GaN based semiconductor lightemitting device is formed into a shape similar to an inverted ship'sbottom depending on the condition of crystal growth on the (0001) planeof a sapphire substrate. The semiconductor light emitting device of thepresent invention may be a semiconductor light emitting device havingsuch a tilt plane.

[0059] Since light emitting diodes representative of semiconductor lightemitting devices are, as described above, of three kinds allowingemission of red light (R), green light (G), and blue light (B) dependingon the materials thereof, it is possible to fabricate a full-color imagedisplay unit having a high luminance by using a combination of theselight emitting diodes of three kinds as pixels. Since the light emittingdiode can be easily changed into a semiconductor laser by providing aresonance mirror thereon, it is possible to fabricate a lighting unit ora traffic sign by using one kind of semiconductor lasers allowingemission of a single color or using three kinds of semiconductor lasersallowing emission of three primary colors.

[0060] Hereinafter, embodiments of the display unit and the fabricationmethod thereof according to the present invention will be described withreference to the drawings.

[0061] (Embodiment 1)

[0062]FIGS. 1 and 2 are sectional views showing a production step ofburying a micro-sized GaN based semiconductor light emitting device 11in a polymer compound, to form a resin-covered chip having a largeapparent size, thereby facilitating the handling of the light emittingdevice 11. Referring to FIG. 1, the GaN based semiconductor lightemitting devices 11, each having a size (which is the length of the longside of the lower end surface) of 100 μm, are disposed on a surface of atransparent support (not shown) with a pitch of 310 μm and are fixedthereon by means of a polyimide adhesive (not shown), and a solution ofan epoxy resin is applied to the GaN based semiconductor light emittingdevices 11 excluding the upper and lower end portions thereof, beingdried, and cured, to form an insulating layer 21, whereby the GaN basedsemiconductor light emitting devices 11 are buried in the insulatinglayer 21. It is noted that one of the GaN based semiconductor lightemitting devices 11 buried in the insulating layer 21 is shown in FIG.1.

[0063]FIGS. 3A and 3B are a sectional view and a plan view showing thedetailed structure of the GaN based semiconductor light emitting device11, respectively. An SiO₂ mask is formed on a (0001) plane of a sapphiresubstrate (not shown). A buffer layer is formed in an opening portion ofthe SiO₂ mask in a flat plate-shape at a temperature of 500° C., and ann-type gallium nitride (GaN:Si) 12 doped with silicon is formed on thebuffer layer in a flat plate-shape at 1000° C. An SiO₂ mask 13 is formedon the n-type gallium nitride 12, and a hexagonal pyramid shaped n-typesemiconductor (GaN:Si) 14 is formed by crystal growth from the openingportion of the SiO₂ mask 13. An active layer 15 made from InGaN isformed on (1-101) planes of the hexagonal pyramid of the n-typesemiconductor 14 and tilt planes equivalent thereto at a growthtemperature lower than 1000° C. A p-type gallium nitride layer (GaN:Mg)16 doped with magnesium is grown on the active layer 15. An Ni/Au filmis then formed on the p-type (GaN:Mg) layer 16 as the surface layerportion by vapor-deposition, to form a p-electrode 18 serving as areflection mirror against light emission. An opening portion is formedin the SiO₂ mask 13 covering the upper surface of the flat-plate shapedunder layer (GaN:Si) 12, and a Ti/Au film is formed in the openingportion of the SiO₂ mask 13 by vapor-deposition, to form an n-electrode19.

[0064] Referring again to FIG. 2, a connection hole 22 is formed in thefirst insulating layer 21, made from an epoxy resin, of the GaN basedsemiconductor light emitting device 11 shown in FIG. 1 to a depthreaching the n-electrode 19 provided on the under layer 12 of the lightemitting device 11. An aluminum film is formed over the entire surfaceof the first insulating layer 21 so as to cover the light emittingdevice 11 by vapor-deposition or sputtering. The aluminum film ispatterned by lithography and etching, to form an extraction electrode18d connected to the p-electrode 18 on the upper end side and anextraction electrode 19 d connected to the n-electrode 19 on the underlayer 12. The first insulating layer 21 is then diced into chips eachhaving a size of 300 μm. It is to be noted that the dicing is performedsuch that the GaN based semiconductor light emitting device 11 islocated at an approximately central portion of the chip. The transparentsupport is irradiated with laser beams, to cause abrasion of thepolyimide adhesive, and then the transparent support is removed from thelight emitting devices 11. In each resin-covered chip having a largeapparent size formed by burying the semiconductor light emitting device11 in the plastic material, the extraction electrodes 18 d and 19 d areconnected to drive circuits. The array of the semiconductor lightemitting devices 11 in the form of the resin-covered chips act as adisplay unit allowing emission of blue light toward the lower endsurface side by injecting a current to each of the semiconductor lightemitting devices 11.

[0065] (Embodiment 2)

[0066]FIGS. 4 and 5 are sectional views showing structures that the GaNbased semiconductor light emitting devices 11 fabricated in Embodiment1, each of which is buried in the first insulating layer 21 to form theresin-covered chip having a size of 300 μm, are fixedly arrayed on theupper surface of a base body 31 in such a manner as to be spaced fromeach other with a specific pitch. Concretely, in the structure shown inFIG. 4, the semiconductor light emitting devices 11 buried in the firstinsulating layer 21 made from an epoxy resin shown in FIG. 2 are fixedlyarrayed on the transparent base body 31 taken as a display panel of adisplay unit in such a manner as to be spaced from each other with apitch of 400 μm. In this case, connection electrodes 32 are provided onthe upper surface of the base body 31 in such a manner as to be spacedfrom each other with a specific pitch, and each of the semiconductorlight emitting devices 11 buried in the first insulating layer 21 isdisposed between two of the connection electrodes 32 and is fixed to theupper surface of the base body 31 by means of a transparent adhesive 33.A solution of an epoxy resin is then applied to cover the entiresurfaces of the semiconductor light emitting devices 11 and theconnection electrodes 32, being dried, and heated to be cured, to form asecond insulating layer 34 made from an epoxy resin.

[0067] Referring to FIG. 5, for each of the semiconductor light emittingdevices 11 shown in FIG. 4, two connection holes 35 and 36 are formed inthe upper surface of the second insulating layer 34 to depths reachingan extraction electrode 18 d of the GaN based semiconductor lightemitting device 11 and reaching the connection electrode 32 on the uppersurface of the base body 31, respectively, and further, a connectionhole 37 is formed in the upper surface of the second insulating layer 34to a depth reaching an extraction electrode 19 d of the GaN basedsemiconductor light emitting device 11. An aluminum film is formed overthe entire surface of the second insulating layer 34 by vapor-depositionor sputtering, and is patterned by lithography and etching, so that ap-electrode 18 of the GaN based semiconductor light emitting device 11is connected to a drive circuit (not shown) on the upper surface of thebase body 31, and an n-electrode 19 of the GaN based semiconductor lightemitting device 11 is connected to a drive circuit (not shown) on theupper surface of the second insulating layer 34. Since the GaN basedsemiconductor light emitting device 11 having a micro size is buried inthe first insulating layer made from an epoxy resin to form aresin-covered chip having a large apparent size as described above, itis possible to facilitate the handling of the semiconductor lightemitting device 11, and since the extraction electrodes 18 d and 19 deach having a large area are provided on the upper surface of the secondinsulating layer 21, it is possible to obtain a merit in facilitatingextraction of the electrodes from the second insulating layer 34 madefrom an epoxy resin in the subsequent step.

[0068] (Embodiment 3)

[0069]FIGS. 6 and 7 are sectional views showing structures that GaNbased semiconductor light emitting devices 11 each having a micro-size,which are not formed into resin-covered chips having large sizes byburying the light emitting devices 11 in an insulating layer but areleft as bared, are fixedly arrayed on the upper surface of a base body31 taken as a display panel of a display unit. Concretely, in thestructure shown in FIG. 6, connection electrodes 32 are provided on theupper surface of the base body 31 in such a manner as to be spaced fromeach other with a specific pitch, and the GaN based semiconductor lightemitting devices 11, each having a size of 100 μm, are picked up asbared by a vacuum attracting chuck, and are disposed on the uppersurface of the base body 31 with a pitch of 400 μm and fixed thereto bymeans of a transparent adhesive 33. In this case, each of the lightemitting devices 11 is located between two of the connection electrodes32. A solution of an epoxy resin is then applied to cover the entiresurfaces of the light emitting devices 11 and the connection electrodes32, being dried, and heated to be cured, to form a second insulatinglayer 34.

[0070] Referring to FIG. 7, for each of the light emitting devices 11shown in FIG. 6, three connection holes 35′, 36′ and 37′ are formed inthe second insulating layer 34 made from an epoxy resin to depthsreaching a p-electrode 18 of the GaN based semiconductor light emittingdevice 11, the connection electrode 32 on the upper surface of the basebody 31, and an n-electrode 19 of an under layer 12 of the GaN basedsemiconductor light emitting device 11, respectively. An aluminum filmis formed over the entire surface of the second insulating layer 34 byvapor-deposition or sputtering, and is patterned by lithography andetching, so that the p-electrode 18 of the GaN based semiconductor lightemitting device 11 is connected to a drive circuit (not shown) on theupper surface of the base body 31, and the n-electrode 19 is connectedto a drive circuit (not shown) on the second insulating layer 34. Evenin this case, since the GaN based semiconductor light emitting devices11, each of which has a micro-sized and is thereby fabricated at a lowcost, are disposed on the upper surface of the base body 31 with aspecific pitch, it is possible to reduce the cost of a display unitfabricated by using the array of the GaN based semiconductor lightemitting devices 11.

[0071] It is to be noted that the display unit and the fabricationmethod thereof according to the present invention are not limited to theabove-described embodiments, and may be variously varied withoutdeparting from the technical thought of the present invention.

[0072] For example, the display unit described in each of Embodiments 1and 2 is fabricated by using the micro-sized hexagonal pyramid shapedGaN based semiconductor light emitting devices 11; however, the displayunit according to the present invention may be fabricated by usinganother type GaN based semiconductor light emitting device having amicro-sized crystal structure. FIG. 8 is a sectional view showing atruncated hexagonal pyramid shaped GaN based semiconductor lightemitting device. In fabrication of this light emitting device, like thefabrication of the hexagonal pyramid shaped semiconductor light emittingdevice shown in FIGS. 3A and 3B, GaN based semiconductor is formed onthe (0001) plane of a sapphire substrate by selective crystal growth. Inthis case, a time required for selective crystal growth is set to beshorter than that for selective crystal growth in the fabrication of thehexagonal pyramid shaped semiconductor light emitting device shown inFIGS. 3A and 3B, to form a truncated hexagonal pyramid shaped n-type(GaN:Si) semiconductor 41. An active layer 45 made from InGaN is formedon the (0001) plane, which is the upper plane parallel to the lower endplane of the n-type (GaN:Si) semiconductor 41, and on (1-101) planesequivalent to the tilt planes of the hexagonal pyramid, and a p-type(GaN:Mg) semiconductor layer 46 is grown on the active layer 45. AnNi/Au film is formed on the p-type (GaN:Mg) semiconductor layer 46 asthe surface layer portion by vapor-deposition, to form a p-electrode 48.An SiO₂ mask 43 is formed on an under layer 42 formed by a flat-plateshaped n-type (GaN:Si) semiconductor, and a Ti/Au film is formed on theupper surface of a portion, exposed from an opening portion of the SiO₂mask 43, of the under layer 42 by vapor-deposition, to form ann-electrode 49. In this light emitting device, the tilt planes and theupper planes of the truncated hexagonal pyramid act as reflectionmirrors against light emission.

[0073]FIG. 9 shows a further GaN based semiconductor light emittingdevice 51 having a crystal structure different from that shown in FIGS.3A and 3B. As shown in this figure, an n-type (GaN:Si) semiconductor isgrown on the (0001) plane of a sapphire substrate, to form an underlayer 52, and an SiO₂ mask 53 is formed on the under layer 52. Arectangular opening portion longer in a <1-100> direction is provided inthe mask 53, and a GaN based semiconductor 51 is formed by selectivecrystal growth from the opening portion of the mask 53. Such a GaN basedsemiconductor 51 is formed into a shape similar to that of an invertedship's bottom, wherein the semiconductor 51 has (1-101) and (11-22)planes. The GaN based semiconductor light emitting device 51 having suchtilt planes can be also used for a display unit.

[0074] In the embodiments, the (0001) plane of the sapphire substrate isused as a plane for crystal growth of a GaN based semiconductor of thesemiconductor light emitting device of the present invention; however,another plane of the sapphire substrate may be used as the crystalgrowth plane, and further, a substrate other than the sapphiresubstrate, for example, a GaN water or an SiC wafer may be used as thesubstrate for crystal growth of a GaN based semiconductor of thesemiconductor light emitting device of the present invention.

[0075] In the embodiments, each of the first and second insulatinglayers is made from an epoxy resin; however, it may be made from athermosetting resin such as a heat-resisting polyimide resin, athermoplastic resin such as vinyl chloride based copolymer, or asynthetic rubber such as polyurethane rubber. Alternatively, each of thefirst and second insulating layers may be formed by depositing aninorganic insulating material such as silicon oxide or silicon nitridein a layer structure.

[0076] In Embodiments 1 and 2, as shown in FIGS. 3A and 3B, the GaNbased semiconductor light emitting device 11 is configured such that thep-type semiconductor 16 is located on the upper side and the n-typesemiconductor 14 is located on the lower side; however, thesemiconductor light emitting device 11 may be replaced with asemiconductor light emitting device configured such that the p-typesemiconductor 16 is located on the lower side and the n-typesemiconductor 14 is located on the upper side.

[0077] In the step of Embodiment 1 shown in FIG. 1, the semiconductorlight emitting device 11 on which the p-electrode 18 and the n-electrode19 have been already provided is used; however, in the step of formingthe conductive metal film by vapor-deposition or sputtering, theelectrodes may be formed and then extracted to the upper surface of thefirst insulating layer.

[0078] In these embodiments, the semiconductor light emitting device isexemplified by the light emitting diode; however, since a semiconductorlaser can be obtained by providing resonators using both end planes ofthe light emitting diode as mirror surfaces, it is possible to fabricatea lighting unit or a traffic sign including one kind of semiconductorlasers allowing emission of a single color or three kinds ofsemiconductor lasers allowing emission of three primary colors.

[0079] The present invention configured as described above has thefollowing effects:

[0080] According to the display unit described in claim 1, since thesemiconductor light emitting devices are fixedly arrayed on the plane ofthe base body at intervals in a state being buried in a first insulatinglayer or in a bare state being not buried in the first insulating layerand are covered with the second insulating layer, followed by extractionof the electrodes of each of the semiconductor light emitting device, itis possible to reduce the occupied area of the semiconductor lightemitting devices per unit area of the display unit and simplify thewiring, and hence to significantly reduce the cost.

[0081] According to the display unit described in claim 2, since each ofthe semiconductor light emitting devices is buried in the firstinsulating layer to form a resin-covered chip having a large size, it ispossible to facilitate the handling of the semiconductor light emittingdevice, and since one electrode is connected to a drive circuit on theupper surface of the second insulating layer and the other electrode isconnected to a drive circuit on the plane of the base body, the drivecircuits for the electrodes located in the directions perpendicular toeach other do not cross each other, so that it is possible to simplifythe wiring and hence to reduce the cost.

[0082] According to the display unit described in claim 3, since thebare semiconductor light emitting devices are used, some ingenuity isrequired in handling the semiconductor light emitting devices; however,it is possible to omit the step of burying the semiconductor lightemitting devices in the first insulating layer, and since one electrodeis connected to a drive circuit on the upper surface of the secondinsulating layer and the other electrode is connected to a drive circuiton the plane of the base body, the drive circuits for the electrodeslocated in the directions perpendicular to each other do not cross eachother, thereby simplifying the wiring.

[0083] According to the display unit described in claim 4, since each ofthe first insulating layer and the second insulating layer is made froma polymer compound formable into a coating film, it is possible tosimply form the insulating layer even on the base body plane having alarge area, and hence to reduce the cost.

[0084] According to the display unit described in claim 5, since thesemiconductor light emitting device has, at a position over the lightemission region, a reflection mirror from which the light is reflecteddownwardly, it is possible to effectively direct light from the lightemission region to the lower end plane of the semiconductor lightemitting device by means of the reflection mirror.

[0085] According to the display unit described in claim 6, since thesemiconductor light emitting device is formed into a pyramid shape or atruncated pyramid shape and any one of at least tilt planes among planesof the pyramid or truncated pyramid shaped semiconductor light emittingdevice is taken as the reflection mirror, the light directed to theupper end portion of the semiconductor light emitting device can be moreeffectively directed to the lower end plane side of the semiconductorlight emitting device.

[0086] According to the display unit described in claim 7, since thesemiconductor light emitting device is made from a gallium nitride basedsemiconductor having a hexagonal system and the semiconductor lightemitting device includes an active layer formed in parallel to a (1-101)plane, it is possible to enhance the light emitting characteristic bytaking an electrode plane provided on the (1-101) plane as a reflectionmirror.

[0087] According to the display unit described in claim 8, there isprovided a display unit according to claim 7, wherein the semiconductorlight emitting device is made from a gallium nitride based semiconductorformed on a substrate by crystal growth with a (0001) plane taken as thelower end plane and (1-101) planes and planes equivalent thereto takenas the tilt planes, and the semiconductor light emitting device includesan active layer formed in parallel to the (1-101) planes and planesequivalent thereto, it is possible to concentrate light emitted from thelight emission region to the lower end plane of the semiconductor lightemitting device by taking electrode planes provided on the tilt planesas reflection planes, and particularly to enhance the light emissioncharacteristic.

[0088] According to the display unit described in claim 9, since thedisplay is configured as an image display unit or a lighting unitincluding an array of only one kind of the semiconductor light emittingdevices allowing emission of light of a single color, or an array of acombination of a plurality of kinds of the semiconductor light emittingdevices allowing emission of light of different colors, such a displayunit is able to exhibit a high luminance.

[0089] According to the method of fabricating a display unit describedin claim 10, since the semiconductor light emitting devices each ofwhich has been buried in the first insulating layer and from each ofwhich the electrodes have been extracted on the first insulating layerare fixedly arrayed on the plane of the base body at intervals andcovered with the second insulating layer, and then the electrodes areextracted on the second insulating layer, it is possible to reduce theoccupied area of the semiconductor light emitting devices per unit areaof the display unit and simplify the wiring, and hence to significantlyreduce the cost of the display unit.

[0090] According to the method of fabricating a display unit describedin claim 11, since each of the semiconductor light emitting devices isburied in the first insulating layer except the upper end portion andthe lower end plane thereof, and the upper end side electrode and thelower end side electrode are extracted to the upper surface of the firstinsulating layer, it is possible to facilitate the extraction of theupper end side electrode, and to avoid a reduction in light emissionplane due to extraction of the electrode to the lower end plane side. Ofcourse, the lower end side electrode can be extracted to the lower endplane side by using a transparent electrode or the like.

[0091] According to the method of fabricating a display unit describedin claim 12, since either of both the electrodes having been extractedon the upper surface of the second insulating layer is connected to theconnection electrode provided on the plane of the base body, both theelectrodes are connected to drive circuits on the upper surface of thesecond insulating layer and on the plane of the base body, respectively,so that it is possible to avoid the drive circuits from crossing eachother, and hence to simplify the wiring.

[0092] According to the method of fabricating a display unit describedin claim 13, since the bare semiconductor light emitting devices arefixedly arrayed on a plane of the base body at intervals and the secondinsulating layer is formed:so as to cover the semiconductor lightemitting devices, some ingenuity is required in handling thesemiconductor light emitting devices; however, the occupied area of thesemiconductor light emitting devices per unit area of the display unitbecomes small, and since the step of burying the semiconductor lightemitting devices in the first insulating layer is omitted, it ispossible to significantly reduce the cost.

[0093] According to the method of fabricating a display unit describedin claim 14, since the upper end side electrode and the lower end sideelectrode of each of the semiconductor light emitting devices areextracted on the upper surface of the second insulating layer, andeither of both the electrodes is connected to the connection electrodeprovided on the plane of the base body, both the electrodes areconnected to drive circuits on the upper surface of the secondinsulating layer and on the plane of the base body, respectively, sothat it is possible to avoid the drive circuits from crossing eachother, and hence to simplify the wiring.

[0094] According to the display unit described in claim 15, since eachof the first insulating layer and the second insulating layer is madefrom a polymer compound formable into a coating film, for example, apolyimide resin or an epoxy resin, it is possible to easily form theinsulating layer even on the plane, having a large area, of the basebody by coating, and to simplify the mounting of the semiconductor lightemitting devices on the plane of the base body, and thereby reduce thecost.

[0095] According to the display unit described in claim 16, since thesemiconductor light emitting device has, at a position over the lightemission region, a reflection mirror from which the light is reflecteddownwardly, it is possible to effectively direct light from the lightemission region to the lower end plane of the semiconductor lightemitting device by means of the reflection mirror.

[0096] According to the method of fabricating a display unit describedin claim 17, since the semiconductor light emitting device is formedinto a pyramid shape or a truncated pyramid shape and any one of atleast tilt planes among planes of the pyramid or truncated pyramidshaped semiconductor light emitting device is taken as the reflectionmirror, it is possible to effectively direct light emitted from thelight emission region to the lower end plane of the semiconductor lightemitting device by means of the reflection mirror.

[0097] According to the method of fabricating a display unit describedin claim 18, since the semiconductor light emitting device is made froma gallium nitride based semiconductor having a hexagonal system, and thesemiconductor light emitting device includes an active layer formed inparallel to a (1-101) plane, it is possible to enhance the lightemission characteristic by using an electrode plane provided on the(1-101) plane as a reflection mirror.

[0098] According to the method of fabricating a display unit describedin claim 19, since the semiconductor light emitting device is made froma gallium nitride based semiconductor formed by crystal growth on agrowth substrate into a hexagonal pyramid shape or a truncated hexagonalpyramid shape with a (0001) plane taken as the lower end plane and(1-101) planes taken as the tilt planes, and the semiconductor lightemitting device includes an active layer formed in parallel to the(1-101) planes, it is possible to enhance the light emissioncharacteristic by using an electrode plane provided on the (1-101) planeas a reflection mirror.

1. A display unit including a plurality of semiconductor light emittingdevices mounted in array on a plane of a base body, characterized inthat said semiconductor light emitting devices are fixedly arrayed onthe plane of said base body at intervals in a state being buried in afirst insulating layer or in a bare state being not buried in said firstinsulating layer; a second insulating layer is formed on the plane ofsaid base body so as to cover said semiconductor light emitting devices;and an upper end side electrode and a lower end side of each of saidsemiconductor light emitting devices are extracted via connection holesformed in specific positions of said first insulating layer and saidsecond insulating layer.
 2. A display unit according to claim 1, whereinsaid semiconductor light emitting devices are fixedly arrayed on theplane of said base body in a state being buried in said first insulatinglayer except the upper end portions and the lower end portions of saidsemiconductor light emitting devices; said upper end side electrode andsaid lower end side electrode of each of said semiconductor lightemitting devices are extracted to the upper surface of said firstinsulating layer and then extracted to the upper surface of said secondinsulating layer; and either of said electrodes is led to a connectionelectrode provided on the plane of said base body.
 3. A display unitaccording to claim 1, wherein said semiconductor light emitting devicesare fixedly arrayed on the plane of said base body in the state beingbared; said second insulating layer is formed on the plane of said basebody so as to cover said semiconductor light emitting devices; saidupper end side electrode and said lower end side electrode of each ofsaid semiconductor light emitting devices are extracted to the uppersurface of said second insulating layer; and either of said electrodesis led to a connection electrode provided on the plane of said basebody.
 4. A display unit according to claim 1, wherein each of said firstinsulating layer and said second insulating layer is made from a polymercompound formable into a coating film, said polymer compound beingselected from a polyimide resin, an ultraviolet curing resin, an epoxyresin, and a synthetic rubber.
 5. A display unit according to claim 1,wherein each of said semiconductor light emitting devices mainly emitslight in a direction from a light emission region to the lower endplane, mounted on the plane of said base body, of said semiconductorlight emitting device; and said semiconductor light emitting device has,at a position over said light emission region, a reflection mirror fromwhich the light is reflected downwardly.
 6. A display unit according toclaim 5, wherein said semiconductor light emitting device is formed intoa pyramid shape or a truncated pyramid shape; and any one of at leasttilt planes among planes of said pyramid or truncated pyramid shapedsemiconductor light emitting device is taken as said reflection mirror.7. A display unit according to claim 6, wherein said semiconductor lightemitting device is made from a gallium nitride based semiconductorhaving a hexagonal system; and said semiconductor light emitting deviceincludes an active layer formed in parallel to a (1-101) plane.
 8. Adisplay unit according to claim 7, wherein said semiconductor lightemitting device is made from a gallium nitride based semiconductorformed by crystal growth on a growth substrate into a hexagonal pyramidshape or a truncated hexagonal pyramid shape with a (0001) plane takenas said lower end plane and (1-101) planes and planes equivalent theretotaken as said tilt planes; and said semiconductor light emitting deviceincludes an active layer formed in parallel to said (1-101) planes andplanes equivalent thereto.
 9. A display unit according to claim 1,wherein said display is an image display unit or a lighting unitincluding an array of only one kind of said semiconductor light emittingdevices allowing emission of light of a single color, or an array of acombination of a plurality of kinds of said semiconductor light emittingdevices allowing emission of light of different colors.
 10. A method offabricating a display unit including a plurality of semiconductor lightemitting devices on a plane of a base body, characterized by includingthe steps of: burying said semiconductor light emitting devices in afirst insulating layer, forming specific connection holes in said firstinsulating layer, and extracting an upper end side electrode and a lowerend side electrode of each of said semiconductor light emitting devicesvia said connection holes formed in said first insulating layer; fixedlyarraying semiconductor light emitting devices, from each of which saidelectrodes have been extracted, on the plane of said base body atintervals; forming a second insulating layer so as to cover saidsemiconductor light emitting devices each of which has been buried insaid first insulating layer; and forming specific connection holes insaid second insulating layer, and extracting said upper end sideelectrode and said lower end side electrode of each of saidsemiconductor light emitting devices having been extracted to the uppersurface of said first insulating layer via said connection holes.
 11. Amethod of fabricating a display unit according to claim 10, wherein eachof said semiconductor light emitting devices is buried in said firstinsulating layer except an upper end portion and a lower end planethereof, and said upper end side electrode and said lower end sideelectrode are extracted to the upper surface of said first insulatinglayer.
 12. A method of fabricating a display unit according to claim 10,wherein said upper end side electrode and said lower end side electrodeof each of said semiconductor light emitting devices having beenextracted to the upper surface of said first insulating layer are bothextracted to the upper surface of said second insulating layer; andeither of said electrodes is led to a connection electrode provided onthe plane of said base body.
 13. A method of fabricating a displayincluding a plurality of semiconductor light emitting devices mounted inarray on a plane of a base body, characterized by including the stepsof: fixedly arraying said semiconductor light emitting devices on theplane of said base body at intervals in a state being bared; forming asecond insulating layer on the plane of said base body so as to coversaid semiconductor light emitting devices; and forming specificconnection holes in said second insulating layer, and extracting anupper end side electrode and a lower end side electrode of each of saidsemiconductor light emitting devices via said connection holes.
 14. Amethod of fabricating a display unit according to claim 13, wherein saidupper end side electrode and said lower end side electrode of each ofsaid semiconductor light emitting devices in the state being bared areextracted to the upper surface of said second insulating layer; andeither of said electrodes is led to a connection electrode provided onthe plane of said base body.
 15. A method of fabricating a display unitaccording to claim 10 or 13, wherein each of said first insulating layerand said second insulating layer is made from a polymer compoundformable into a coating film, said polymer compound being selected froma polyimide resin, an ultraviolet curing resin, an epoxy resin, or asynthetic rubber.
 16. A method of fabricating a display unit accordingto claim 10 or 13, wherein each of said semiconductor light emittingdevices mainly emits light in a direction from a light emission regionto the lower end plane, mounted on the plane of said base body, of saidsemiconductor light emitting device; and said semiconductor lightemitting device has, at a position over said light emission region, areflection mirror from which the light is reflected downwardly.
 17. Amethod of fabricating a display unit according to claim 16, wherein saidsemiconductor light emitting device is formed into a pyramid shape or atruncated pyramid shape; and any one of at least tilt planes amongplanes of said pyramid or truncated pyramid shaped semiconductor lightemitting device is taken as said reflection mirror.
 18. A method offabricating a display unit according to claim 17, wherein saidsemiconductor light emitting device is made from a gallium nitride basedsemiconductor having a hexagonal system; and said semiconductor lightemitting device includes an active layer formed in parallel to a (1-101)plane.
 19. A method of fabricating a display unit according to claim 18,wherein said semiconductor light emitting device is made from a galliumnitride based semiconductor formed by crystal growth on a growthsubstrate into a hexagonal pyramid shape or a truncated hexagonalpyramid shape with a (0001) plane taken as said lower end plane and(1-101) planes and planes equivalent thereto taken as said tilt planes;and said semiconductor light emitting device includes an active layerformed in parallel to said (1-101) planes and planes equivalent thereto.